Deep Space Settlement is a 4X real-time strategy game focused on empire building and grand-scale space battle.
You might remember the planetoid concept from last year: Indiedb.com
I'm working on refining that and bringing it into the game. The current idea is to have them mine-able after they have been cracked open. This could be done using a significant amount of fire power, or maybe using some tech, it's not clear yet. But essentially, there's a good amount of resources inside of these, that aren't available to the player right from the start. You have to work for them.